A transition method commonly used in television and other film production is the standard cut, which simply moves from one shot to the next without any fanfare or special effects. Fade in -- moving quickly from frames of black to the picture -- and fade out -- going to black at the end of the shot -- are also popular. Transitions that are used less often include the dissolve and various "creative" versions of the wipe.
A dissolve is when one shot fades out while another one fades in simultaneously. The result is a blurring together of two images. This effect is often used to indicate the passage of time, flashbacks or dream sequences.